Process for manufacturing porous articles of clay



Patented Mar.28,1938 I 2,151,932

' UNITED STATES'PATENT OFFICE PROCESS FOR MANUFACTURING POROUS ARTICLES OF CLAY A Aage Nielsen, Copenhagen, Denmark No Drawing. Application June 8, 1931, Serial No. 543,026. Renewed September 21, 1934. In Denmark April 30, 1931 2 Claims. (01. 108-11) The present invention relates to a process for cal means, such a consistency that it can be manufacturing, porous articles of clay and to armoulded in normal manner. ticles manufactured according to this process, I By avoiding, in this manner, an increased adand has for its object to reduce to a minimum mixture of water to the mass of clay, the ad- 5 the quantity of water used in the manufacture. vantage is attained that one is entirely at liberty 5 It is well known to manufacture porous articles to determine how long the mass of clay is to be of clay by causing air to be injected into the .maintained in liq d consistency. mass of clay. It is also known to produce such The means requ ed for working the process articles from clay by mixing a foam-producing are known per se.

1o substance into the mass of clay, after which the The means used for preparing slip masses are 1 thus formed mixture is caused to foam by forcealkaline hydroxides or salts of alkaiies and weak ful working of the mass, or by a generation of acids, such as potash, soda, water glass, etc., air within the same, or by supplying air thereto. which substances modify the colloidal structure It is further known to mix the mass of clay with of the mass of clay and, thereby, cause the mass I a previously formed foam, whereby the mass'beof clay to become liquid, when the admixture-is 15 comes porous. efiected inside of certain definite limits known These processes require the mass of clay emin each individual case by those skilled in the ployed to be of a not too stiff consistency. A art. suitable consistency is generally produced by ad- The porosity is then produced in one of the dition of water. I above described manners and the mass of clay Such an addition of water, however, has for thus treated is returned to a more solid consistits consequence in moulding the clay articles from ency either by further addition of one of the the p rous mass that the moulding methods means prev y used for bringing the mass of known from the manufacture of ordinary n nclay into the liquid consistency or by an addition porous clay masses cannot be used, as the porous o Sp Substances known for this P p 25 mass of clay is too liquid to retain its shape. It for instance sodium chloride, sodium sulphate, is thus, for instance, not practical to produce calcium Sulphate. a m 1 m n sium chloride porous tiles in the ordinarily used manner. If or like substances. the liquid consistency is produced by increased The process may be used for the production of 80 addition of water, the porous tiles have to be coarse as well as fine ceramic articles.

cast, and the porous mass of clay has then to What I claim as new is: remain for quite a long time in the moulds, be- 1. Process for the manufacture of porous cefore the latter can be removed. Further the ramic articles of argillaceous materials, consistincreased addition. of water causes an increased 111g n the following steps, first add n d flo ou- '86 shrinkage during the drying process, whereby lants to a stiff plastic mass of clay then making 85 drying without formation of cracks becomes difnthe thus produced fluid ma Porous y cult. 7 porating gasestherein and finally adding floc- The .present invention relates to a process l n to h porous fluid moss and m in whereby these drawbacks-are remedied entirely. the thus Produced rcstiflcned Porous moss in 40 This object is attained by causing the mass of k w m 0 clay to become liquid by addition of the means The method of making li h w ht por us d for producing slip or "casting-slip" from ceramic material which comprises mixing clay potters clay,-without the addition of water. The with a soluble silicate solution, foaming such liquid mass of clay produced in this mannerv is mixture and introducing a chemical to bring 4| then rendered porous in one of the above deabout stifieningthereof. 5

scribed'manners, and the time produced porous AAGE NIELSEN. mass of clay is then given, by additionof chemi- 

